The document discusses alternating current, how it is generated using electromagnetic induction from rotating coils in magnetic fields, and the working principles of AC generators used widely in power plants and vehicles to convert mechanical energy into electrical energy for power grids and other applications. Major topics covered include the differences between AC and DC, methods for changing magnetic flux to generate AC, components and efficiency of AC generators, and their predominant uses.

1. ART
INTEGRATED
ACTIVITY
SUBJECT - PHYSICS
NEW BEERSHEBA PUBLIC SCHOOL
- HARSHVARDHAN OJHA
Class 12th “c”
Roll no 19
Topic – Alternating Current

2. ● Firstly , I would like to express my special thanks of gratitude to my
teacher Mr. Sanjay Pandey who guided us for this activity , and helped me
in doing a lot research and I came to know about so many things
ACKNOWLEDGEMENT
● Secondly, I would also like to thank my friends who helped me a lot in
finalising this activity in limited time frame

3. Certificate
This is to certify that Harshvardhan Ojha , a student of class XII-C has
successfully completed the research on the below mentioned project , under
the guidance of Mr. Sanjay Pandey , during the year 2020-21 in practical
fulfillment Conducted by CBSE New Delhi

4. Introduction to AC
● As useful and as easy to understand as DC is, it is
not the only “kind” of electricity in use. Certain
sources of electricity (most notably, rotary
electromechanical generators) naturally produce
voltages alternating in polarity, reversing positive
and negative over time.
● Either as a voltage switching polarity or as a current
switching direction back and forth, this “kind” of
electricity is known as Alternating Current

5. On What Principal AC generated?
It works on the principal of Electromagnetic Induction (EMI) , given by Michael Faraday
Statement :-
Whenever magnetic flux link with any coil changes then an induced EMF produced
and if the coil is closed the induced current flows through coil.
The induced current lasts as long as the magnetic flux link through the coil
changes
No of magnetic field lines passing perpendicularly through any surface
Magnetic flux
Given by - ∅𝐵 = 𝐵𝐴 cos 𝜃
B – MAGNETIC FIELD
A – AREA

6. 4
PLAN
PLAN
3
PLAN
2
PLAN
1
RELATIVE MOTION
Changing field
lines produce
induced current
VARIABLE M.FIELD
Changing magnitude
of field produce
induce current
VARIABLE AREA
Changing area link
to flux produce
induce current
CHANGING ANGLE
Changing angle btw
field and area
produce induce current
METHODS TO CHANGE M.FLUX

7. METHODS OF CHANGING MAGNETIC FLUX LINK WITH ANY COIL
N S
G
01. 02.
03. 04.
I
(BY RELATIVE MOTION BETWEEN COIL AND MAGNET) (BY KEEPING COIL IN VARIABLE MAGNETIC FIELD)
(BY CHANGING AREA OF COIL BOUNDED IN MAGNETIC FIELD) (DUE TO ROTATION OF COIL IN MAGNETIC FIELD)
coil
Changing coil area by moving
Rotatingcoil in field

8. Advantage of AC over DC
Alternating Current Direct Current
AC is safe to transfer longer distance even between two
cities, and maintain the electric power.
DC cannot travel for a very long distance. It loses
electric power.
The rotating magnets cause the change in direction of
electric flow.
The steady magnetism makes DC flow in a single
direction.
The frequency of AC is depended upon the country. But,
generally, the frequency is 50 Hz or 60 Hz.
DC has no frequency of zero frequency.
In AC the flow of current changes its direction
backwards periodically.
It flows in a single direction steadily.
Electrons in AC keep changing its directions – backward
and forward
Electrons only move in one direction – that is forward.

9. Graph comparison between AC and DC
v
t
Alternating current :-
Direct current :-
(constant – magnitude , direction)
(Periodically changing – magnitude , direction
with time)
𝐼 = 𝐼𝑜𝑠𝑖𝑛𝜔𝑡
EQUATION OF ALTERNATING CURRRENT
FROM GRAPH – AC change its direction and magnitude in every time “t”

10. MAJOR ENERGY GENERATING PLANTS IN INDIA
THERMAL
BY BURNING COAL , FUEL ETC
AND BOILING WATER PRODUCE
STEAM WHICH ROTATE THE
COIL OF GENERATOR
HYDRO
THE HEAVY FLOW OF WATER
THROUGH ANY RESERVOIR
ROTATES THE COIL OF
GENERATOR
NUCLEAR
NUCLEAR REACTION IS DONE
TO BOIL THE WATER, THUS
THE STEAM PRODUCE
ROTATES THE COIL
OTHERS
WIND ENERGY , BIO GAS ,
SOLAR ENERGY ETC IS USED
TO ROTATE THE COIL OF
GENERATOR

11. INDIA’s Electricity Generation
Hydro power plant
Others (gas , solar , wind etc)
Nuclear power plant
Thermal power plant
About 65% of the electricity consumed in India is generated by thermal power plants, 22% by hydroelectric power
plants, 3% by nuclear power plants and rest by 10% from other alternate sources like solar, wind, biomass etc
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
source -google

12. • AC generator helps us to convert mechanical
energy into electrical energy.
AC generator was invented by Sir Nicola Tesla
• The source of mechanical energy can be
steam turbines ,gas turbines or internal
combustion engines and mostly wind
,hydropower or tidal resources.
• AC generators provides about all the power for
the electric power grids
Introduction to AC Generator

13. PRINCIPAL
Working of AC generator is based on the principal of
Electromagnetic Induction
Whenever magnetic flux link with any coil changes then
induced emf and current is set up on it

14. The main components of AC generator are :-
ARMATURE COIL : It is a rectangular coil consist of large no of turns of
insulated copper wire
STRONG MAGNETS : Magnets of different polarity are used to produce field
SLIP RINGS : The end of armature is connected to two hollow rings called
slip rings
CARBON BRUSHES : The two brushes connected to slip rings are made of carbon
and provides link with external circuit and supports system
CONSTRUCTION

15. Working of AC Generator :
ROTATION
The armature coil is rotated with
the help of external means
FLUX CHANGE
Due to rotation , magnetic flux of coil
changes and induced emf is produced
Formation of AC
If the coil is closed an induced current
flows through coil called AC

16. AC CURRENT DEPENDS ON:-
The speed at which the conductor experiences
a changing magnetic field
The number of coils that make
up the conductor
The position of the plane of the
conductor with respect to the
magnetic field
The amount of current depends on:

17. EFFICIENCY OF AC GENERATOR
Efficiency of an AC generator is the ratio of the useful power output
to the total power input. Because any mechanical process
experiences some losses, no AC generators can be 100 percent
efficient. Efficiency of an AC generator can be calculated using
below Equation :-

18. Problem and its Solution
Hysteresis losses occur when iron cores in an AC generator
are subject to effects from a magnetic field. The magnetic
domains of the cores are held in alignment with the field in
varying numbers, dependent upon field strength. The
magnetic domains rotate, with respect to the domains not
held in alignment, one complete turn during each rotation
of the rotor. This rotation of magnetic domains in the iron
causes friction and heat. The heat produced by this friction
is called magnetic hysteresis loss
Problem Solution
To reduce hysteresis losses, most AC armatures
are constructed of heat-treated silicon steel,
which has an inherently low hysteresis loss.
After the heat-treated silicon steel is formed to
the desired shape, the laminations are heated
to a dull red and then allowed to cool. This
process, known as annealing, reduces
hysteresis losses to a very low value.
BASIC ENERGY LOSS IN AC GENERATOR
Hysteresis losses

19. Major Uses of AC generator
Turbine generator
Computer fans , coffee
machine , ceiling fans ,
mixer etc
Alternos
In automobiles ,
The generators are called
ALTERNOS
Small electric items
This device is used
in power plants to
generate electricity
30% 50% 90%
Major uses of ac generator is to make the following devices

20. Bibliography
• MR . SANJAY PANDEY (PHYSICS TEACHER)
• NCERT TEXTBOOK
• WIKIPEDIA
• WEBSITES – WWW.GOOGLE.COM , WWW.QUORA.COM